Added quarter-comma meantone.
Removed duplication from temperament tests.
Refactored tests to remove more duplication.
Improved fact docstring.
Improved the defn of cent.
Privatise some vars not intended for external use.
Extracted alignment into a separate fn.
Extracted the common pattern between Pythagorean and meantone temperaments.
Unified equal temperament with meantone/Pythagorean.
Small refactoring improvements to the tune fn.
Renamed Pythagorean tuning to just for brevity.